Peer-to-peer email

ABSTRACT

A peer-to-peer email system and methods are provided for distributed email distribution, prevention of SPAM, and efficient email storage. Each email client also serves as a node in the peer-to-peer system, relaying email messages and/or attachments. Large attachments may be transmitted directly from sender to receiver, and if the receiver is not online at the time the sender sends the attachment, the receiver can request the attachment from the sender at a later time.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of a prior filed and currentlypending application having Ser. No. 13/586,730 and a filing date of Aug.15, 2012.

This application claims priority and is entitled to the priority date ofU.S. non-provisional application Ser. No. 13/586,730, filed on Aug. 15,2012 (U.S. Pat. No. 9,166,937), which is a continuation of U.S.non-provisional application Ser. No. 12/276,114, filed on Nov. 21, 2008,now abandoned, which claims priority and is entitled to the filing dateof U.S. provisional application Ser. No. 60/989,774, filed on Nov. 21,2007. The contents of the aforementioned applications are incorporatedby reference herein.

BACKGROUND

Existing email systems may be centrally controlled. Simple MailTransport Protocol (“SMTP”) is the de facto standard used on theinternet today. A first SMTP server (e.g., mail.yin.com) may receiveemail messages from SMTP clients (e.g., Microsoft® Outlook, Mozilla®Thunderbird) executing on computers in the first SMTP server's domain.The email messages may include one or more recipient email addresses(e.g., john @yang.net). The first SMTP server may route the receivedmessages to a second SMTP server on the intended recipient's domain(e.g., mail.yang.net) using known systems such as the domain name system(“DNS”). After receiving the email message, the second SMTP server maydeliver the email messages to the intended recipient's mailbox, whichmay be stored on the second SMTP server and made available to theintended recipient over the network.

SMTP servers may be configured to restrict the size of attachments whichmay be sent with an email message. Other SMTP servers may limit theamount of storage space (i.e., the size of a mailbox) allocated to auser to store emails and attachments. Still other SMTP servers may notprotect or offer the capability of protecting emails and attachmentsassociated therewith from malicious or otherwise unintended recipients,either locally or while in transit over a computer network.

In addition to the above, unsolicited advertising emails (“SPAM”) areubiquitous on the Internet. It is estimated by some that as of 2007, 90billion SPAM messages are sent every day, and that so-called “abusiveemail” accounts for up to 85% of incoming mail in a given email inbox.

Finally, existing email systems exhibit various inefficiencies. Forinstance, centralized email server farms are estimated to consume overtwo billion dollars' worth of energy annually around the world. Inaddition, current methods of encoding attachments involve the use ofbase64, which encodes attachments as 7-bit representations, rather thantraditional 8-bit. Base64 introduces approximately 30% of overhead toeach attachment sent. Some estimate that attachments make up 80% ofemail traffic on the Internet. CPU cycles are also required to performthis encoding on the sending user's computer, as well as perform thedecoding on the recipient user's computer.

Aspects of the present invention fulfill these needs and provide furtherrelated advantages as described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate aspects of the present invention.In such drawings:

FIG. 1 depicts an example email system, in accordance with at least oneembodiment;

FIGS. 2A-E depict an email transmission on a system where the sender andthe intended recipient are both online simultaneously, in accordancewith at least one embodiment;

FIGS. 3A-H depict an email transmission on a system where the intendedrecipient is offline, in accordance with at least one embodiment;

FIG. 4 depicts an example method of preventing unsolicited emails, inaccordance with at least one embodiment; and

FIG. 5 depicts a computer using webmail from a remote location to obtaina user's email from his or her computer, in accordance with at least oneembodiment.

The above described drawing figures illustrate aspects of the inventionin at least one of its exemplary embodiments, which are further definedin detail in the following description. Features, elements, and aspectsof the invention that are referenced by the same numerals in differentfigures represent the same, equivalent, or similar features, elements,or aspects, in accordance with one or more embodiments.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

A Peer-to-Peer (“P2P”) email and social networking system is providedfor use by a plurality of users to exchange emails and attachments. Sucha system may be controlled by one or more central servers, or it may becontrolled by decentralized services distributed over a mesh network.Such a mesh network may comprise a plurality of node computers, eachrunning a P2P email client according to the present disclosure. Nodecomputers may be alternatively referred to as “peers.” Emails may bestored in mailboxes residing on each node, rather than centrallylocated. The system may encrypt emails during transmission, and theemails may remain encrypted while stored at each node computer.

In some embodiments, the system may allow the user of each node computerto configure her email client with the user's interests (e.g.,kayaking). Those interests may be communicated to a central server ordecentralized distributed service, where they may be associated with theuser's email address, so that potential advertisers may search byinterest type, and send solicited emails to users associated with thesearched-for interest types.

In other embodiments, the system may be configured to provide remoteaccess to the user's local email when the user is away from her localcomputer. Such access may be provided via a webmail webpage interfacingvia a secure tunnel to the user's local email store.

FIG. 1 depicts an example P2P email system 10 comprising node computerssuch as sender 20 and recipient 30. Sender 20 may be a computercontrolled by a first user intending to send an email message to arecipient 30. Recipient 30 likewise may be a computer controlled by asecond user who is the intended recipient of the email message. Sender20 and recipient 30 may be connected by a network 40. Sender 20 mayinclude an email client 22, a local email store 24, and an email agent26. Recipient 30 likewise may include an email client 32, a local emailstore 34, and an email agent 36.

Network 40 may be a local or wide-area computer network, including theInternet. The P2P email system 10 may be controlled by components onnetwork 40, such as decentralized distributed services 42 includingidentity manager 44, presence manager 46, delivery manager 48, andcontact store 49, as well as cache servers 50. The distributed services42 will be described in further detail below. While decentralizeddistributed services 42 are shown having the four components 44, 46, 48and 49 as being separate, these components may alternatively reside on asingle server, and there may be more than one server hosting one or moreof these services. Moreover, additional services which are not shown(e.g., a gateway server for sending emails to traditional email domains)may also be included.

Email clients 22 and 32 may include user interfaces resemblingtraditional email clients (e.g., Outlook, Thunderbird), and may beconfigured to allow a user to draft, send and receive P2P emails. Emailclients 22 and 32 may further include interfaces allowing a user toselect interests (e.g., kayaking, dating), which may be communicated todecentralized distributed services 42 so that potential advertisers maycommunicate solicited emails to clients 22 and 32, as will be discussedfurther below.

Local email stores 24 and 34 may be portions of memory (e.g., on a localhard drive) which may be used to store email messages and associatedattachments. In other words, local email stores 24 and 34 may servesimilar roles as mailboxes on traditional SMTP servers. Messages storedin local email stores 24 and 34 may be encrypted. The amount of spaceallocated to a user may be configured, and in some embodiments may belimited only by the computer's storage capabilities. In addition toemails and attachments, local mail stores 24 and 34 may store interestinformation (a.k.a. user metadata), user contacts (e.g., the user'sfriends residing on P2P email system and elsewhere), user profiles(e.g., photos available for viewing, whom may view the photos, personalinformation and to whom it is available), group membership (e.g., openor closed groups of users of P2P email system 10 having commoninterests/metadata/contacts) or the like. Interest information,contacts, profiles and other similar information may be configured by auser using email clients such as 22 or 32.

Email agents 26 and 36 may be processes executing on node computers suchas sender 20 or recipient 30 forming the P2P network. While a computersuch as sender 20 or recipient 30 is connected to network 40 and isexecuting its email agent (26 or 36), that computer may be considered‘online’ for purposes of the P2P network and this discussion.

Contact store 49 may be a central server or servers, or it may be aservice distributed among various nodes in the P2P email system 10. Itmay contain information allowing peers on P2P email system 10 to locateother peers, including information similar to that stored in local emailstores described above like interest information, contacts, metadata,group membership, and the like. Peers may be searched at contact store49 using various search values, such as interests, group membership,friendship networks, personal profiles, and the like. In someembodiments, users may synchronize information stored in their localemail stores 24, 34 such as metadata, profiles, and contacts withinformation contained in contact store 49. In other embodiments wherecontact store 49 is a service distributed among various nodes, there maybe a central contact store (not shown) which is configured tosynchronize all nodes on which contact store 49 is contained.

Cache servers 50 may comprise one or more computers on network 40 whichmay be used as intermediate points in email communications betweencomputers such as sender 20 and recipient 30. Cache servers 50 may beconfigured to cache at least a portion of email messages, as well asattachments thereto. In some embodiments, each cache server may be anode computer, similar to sender 20 or receiver 30, forming another peeron the P2P system. Additionally or alternatively, cache servers 50 maybe specialized computers maintained specifically for the purpose ofcaching emails. In some embodiments, cache servers may only cacheattachments having a size smaller than a predetermined size (e.g., <50Megabytes).

A given email message in transition between sender 20 and recipient 30may be stored at a number of cache servers 50 while awaiting delivery,providing redundancy and high availability of the email message torecipient 30 in case some of the cache servers become unavailable (e.g.,go offline). Moreover, cache servers 50, which may simply be peers ornode computers on P2P system 10, may be configured to forward emailmessages to other intermediate peers closer to the recipient'sdestination. Additionally or alternatively, if a given cache server isgoing to go offline, it may forward copies of its stored pending emailmessages/attachments and/or notify the P2P email system of the email'snew location.

The P2P email system 10 will now be explained by example. An exampleemail communication between two node computers 20 and 30, which areonline simultaneously, is shown in FIGS. 2A-E. In step 1 of FIG. 2A,email client application 22 submits an email message created by a firstuser to email agent 26. In step 2 of FIG. 2B, email agent 26communicates with identity manager 44 to verify the recipient emailaddress(es) contained in the email message, and to obtain one or morepublic keys corresponding to the verified email address(es). The publickeys may be used by email agent 26 to encrypt the email message and/orany the message's attachments.

Identity manager 44 may take various forms. In some embodiments,identity manager 44 may be a central database running a hash table orsimilar data structure for relating email addresses to public keys. Inother embodiments, identity manager 44 may be a distributed hash table(“DHT”), such as Content Addressable Network (“CAN”), Chord, Kademlia,Pastry, P-Grid, Tapestry or NeoNet, to name a few. DHTs are a class ofdecentralized distributed systems that provide a lookup service similarto a hash table. They are well-known in the art, and therefore need notbe described further here. Email addresses such as the recipient emailaddress may comprise the names of the hash table, and the value(s)corresponding to each name may be one or more public keys. Email agentssuch as 36 each may possess private keys usable to decrypt messagesencrypted with the one or more public keys.

In step 3 of FIG. 2C, sender email agent 26 may communicate withpresence manager 46 to determine whether recipient 30 is online. Ifrecipient 30 is online, sender email agent 26 may obtain recipient'snetwork address (e.g., IP address).

Presence manager 46 may be a central server configured to track thepresence of email clients and make that information available to emailagents such as 26 and 36. Presence manager may be a central server ordecentralized service, implementing various protocols, such as theExtensible Messaging and Presence Protocol (“XMPP”), for real-time ornear-real-time presence information. Jabber Instant Messaging andPresence technology is based on XMPP, and may be used in someembodiments as presence manager 46.

Once sender email agent 26 has obtained the network address of recipient30 from presence manager 46, sender email agent 26 may transmit theemail message and any attachments thereto directly to recipient emailagent 36 in step 4 of FIG. 2D. When recipient email agent 36 receivesthe email message, in step 5 of FIG. 2D, it may store the email message(which may remain encrypted) and attachments thereto in local emailstore 34.

When the user of recipient 30 executes email client 32 to check heremail, in step 6 of FIG. 2E, recipient email client 32 may communicatewith local email store 34 to obtain all recipient's email messages,including the newest message just received, as well as any attachmentsthereto. If the messages are encrypted, email client 32 may use itsprivate key, corresponding to the public key described above, to decryptmessages.

The above discussion describes an email transmission where both sender20 and recipient 30 are online simultaneously. However, there is noguarantee that recipient 30 will be online at the moment sender 30transmits an email message. FIGS. 3A-H and the following discussiondescribe one possible way an email may be transmitted between sender 20and recipient 30 under such a scenario.

In step 100 shown in FIG. 3A, similar to step 1 of FIG. 2A, email clientapplication 22 submits an email message created by a user to email agent26. Similar to step 2 in FIG. 2B, in step 102 of FIG. 3B, email agent 26connects to identity manager 44 to verify the recipient email addressescontained in the email message, and to obtain public keys correspondingto the verified email addresses. And again, in step 104 in FIG. 3C,sender email agent 26 communicates with presence manager 46 to determinewhether recipient 30 is online.

In the previous example, recipient 30 was online, and thereforeavailable to receive the email message and attachments directly fromsender 20. However, in this example, recipient 30 is offline. Therefore,in step 106 of FIG. 3D, sender email agent 24 may communicate themessage body of the email message and any attachments having a size lessthan a predetermined amount to cache servers 50 residing on network 40.In some embodiments, attachments having sizes greater than thepredetermined amount may remain stored locally on sender 20. In step 108of FIG. 3E, sender email agent 26 may notify delivery manager 48 thatthere are pending messages stored in network 40, as well as where thosepending message may be located (e.g., on which cache servers 50 themessage is cached).

In some embodiments, delivery manager 48 may be a central serverconfigured to store information regarding pending P2P email messagesstored in network 40. In other embodiments, delivery manager 48 may be adecentralized service such as a DHT or other similar distributedsystems.

In some embodiments where delivery manager 48 is a DHT, the names may berecipient email addresses, and the values associated therewith mayinclude information necessary for recipient email agent 36 to obtainpending email messages from network 40. Such information may includeaddress information associated with particular cache servers 50 havingcached copies of the pending email. The address information may be anetwork address of the particular cache servers 50 storing the pendingemails, or, if each cache server is merely another node similar to 20 or30, the address information may be an email address associated with eachnode.

In other embodiments, each email message or attachment may have a uniqueUniversal Resource Name (“URN”). Recipient email agent 36 may benotified of any URNs associated with email messages or attachmentsdestined for recipient 30. A delivery manager 48 implementing a DHT mayuse URNs related to pending email messages and attachments as names, andthe value(s) associated with each URN may be a Universal ResourceLocator (“URL”). The URL may indicate where the email message/attachmentidentified by a URN may be found, as well as what method may be used toobtain the message/attachment (e.g, ftp://www.yin.comlattachment.jpgindicates that the file ‘attachment.jpg’ may be obtained from the domainyin.com using the ftp protocol).

Accordingly, when recipient 30 comes online, in step 110 of FIG. 3F,recipient email agent 36 may communicate with delivery manager 48 todetermine whether there are pending email messages on network 40 whichare intended for recipient 30 and to identify one or more cache servers50 where those messages are located. In some embodiments, recipientemail agent 36 may next communicate with presence manager 44 todetermine which of the identified nodes are currently online and thosenodes' network addresses.

Next, in step 112 of FIG. 3G, recipient local email store 34 (oralternatively, recipient email agent 36) may communicate with theidentified nodes of the cache servers 50 to retrieve message bodies andattachments having a size less than the predetermined amount describedabove.

Attachments larger than the predetermined size may be obtained from theoriginal sender 30, assuming sender 30 is currently online. If sender 20is not currently online, recipient 30 may periodically query presencemanager 46 so that when sender 20 comes back online, recipient 30 maythen obtain the large attachment directly from sender 20.

In some embodiments, where local email store 34 or email agent 36 mustdownload multiple emails from cache servers 50, it may prioritize whichemails/attachments will be retrieved first. For instance, an emailclient 32 may provide an interface for a user to edit contacts and sortthem by various criterion (e.g., degrees of separation of friendship,age, etc.). Using this priority information, email client 32 or agent 36may retrieve emails/attachments in the order of which its contacts havebeen sorted by the user. This priority information may be synchronizedwith contact store 49 when convenient.

When the user of recipient device wishes to read the receivedmessage(s), he or she may use recipient email client 32 to view emailmessages, including newly received messages, stored in local email store34 in step 108 of FIG. 3H.

In some embodiments, sender 20 may be configured to verify thatrecipient 30 received the email address. For instance, recipient emailagent 36 may send an acknowledgement to sender 20 once recipient localemail store 34 has received and stored the entirety of the email and anyattachments thereto. Additionally or alternatively, Sender 20 may queryrecipient 30 to determine whether recipient 30 received the message. Insome embodiments, recipient 30 may notify one of the services indecentralized distributed services 42 (e.g., delivery manager 48) that amessage having a particular URN has been delivered. In such a case,sender 20 may verify that the message was received by communicating withthe services 42.

In the P2P email system disclosed herein, some embodiments may beconfigured to prevent unsolicited email and/or provide users with emailsrelated to topics of interest. Turning to FIG. 4, in step 200, anadvertiser 62 of a particular interest (e.g., a kayak manufacturer) maycommunicate with decentralized distributed services 42 to uploadadvertisement information, which may include metadata such as keywords(e.g., kayak) as well as advertising emails and/or attachments. Emailclient 22 may include an interface including a list 60 of selectableinterests. A user of email client 22 may choose one or more interestsfrom list 60 in step 202, and those choices may be communicated todecentralized distributed services 42 (e.g., to delivery manager 48) instep 204. In step 206, email agent 26 may “pull” down the advertisementsuploaded by advertiser 62 in step 200. Note that because sender 20indicated interest in kayaks, the email sent in step 206 is notunsolicited.

In some embodiments, advertisers such as 62 may be charged a fee foreach of their advertisement emails “pulled” from the system 10.Additionally or alternatively, a ratings system similar to those used intelevision (e.g., Nielsen ratings, which are based on the habits of homeTV viewers) may be implemented to ascertain how much a givenadvertisement is “pulled,” for purposes of charging advertisers such as62.

In another aspect, a user who is away from her computer containing herP2P emails may nevertheless wish to access those emails. In traditionalemail systems (e.g., SMTP), such a user may have access to a webmailinterface, which may comprise a HTML page which the user may access witha web browser. The user may enter her login information (e.g., ausername and password), and upon successful authentication, the webpagemay direct the user's web browser to a second webpage which allows theuser to view, manipulate, and create/send new email messages. Thissecond web page may obtain email data from and interface with the samemail server (containing the user's mailbox) which the user wouldnormally log into with her local computer.

Webmail access similarly may be possible in some embodiments of thedisclosed P2P email system 10. Referring to FIG. 5, a user may be awayfrom her computer 20, but may wish to access email on her local emailstore 24 using a remote computer 70. A central server or one of thedecentralized distributed services 42 (such as delivery manager 48) mayinclude a webmail service. In step 300, the user may connect to thewebmail service executing on decentralized distributed services 42 andprovide login credentials to a login webpage. Upon successfulauthentication, the user may be redirected to a second webpage givingthe user email access. Instead of communicating with the user's mailboxon a central SMTP server, however, in step 302, the second webpage maycommunicate with the user's local email store 24 through a secure tunnel72 to the user's computer 20.

Although the above examples only describe the exchange of email messagesbetween two node computers on P2P system 10, those skilled in the artwill understand that communications may occur between any number of nodecomputers. Moreover, communications may occur between a node computer onP2P system 10 and a traditional email system (e.g., hotmail, gmail,etc.).

For example, one of the decentralized distributed services (e.g., aseparate gateway server which is not shown) may be identified as a mailexchanger (MX) in a DNS. The Gateway server therefore may receive emailmessages/attachments sent from traditional email systems, destined for arecipient residing on the disclosed P2P email system 10, and communicatethose messages to the appropriate recipients using the above-describedmethods (depending on whether the user is online or offline).

Likewise, if a user on a node computer of P2P email system 10 desires tosend an email message to an outside traditional email address, the usermay communicate the message and any attachments to the gateway server.The gateway server may forward the message to the appropriate SMTPserver using MX records in the DNS. In some embodiments, identitymanager 44 may be configured with an index of domains that are part ofP2P email system 10. When sender 20 verifies the email address, such asin step 2 in FIG. 2B or step 102 in FIG. 3B, identity manager 44 maydetermine whether the recipient email address(es) are within the P2Pemail system 10. If so, the process may proceed as described above. If arecipient email address is destined for an outside domain unrelated tothe P2P email system 10, however, sender 20 may be required to forwardthe email and any attachments to the gateway server for delivery to theoutside domain.

In another aspect of the disclosure, the P2P email system 10 may provideefficient attachment distribution. In some instances, instead of usingbase64 to encode attachments to 7-bit representations, the P2P emailsystem 10 may determine the URLs of attachments and make those URLsavailable through decentralized distributed services 42. For instance,assume sender 20 sends an email message including a large attachment(i.e., too large to be stored on cache servers 50) to recipient 30. Alsoassume recipient 30 is online simultaneously with sender 20. The emailreceived by recipient 30 may not include the large attachment, encodedusing Base64 or otherwise. Instead, the email received by recipient 30may include a hyperlink (URL) to a location on sender 20 containing thelarge attachment, so that recipient 30 may initiate a connection tosender 20 and download the large attachment directly (e.g., using FTP,HTTP, BitTorrent, or other well-known transfer protocols). Theinitiation of the file transfer may not require intervention by the userof recipient 30. Instead, recipient email client 32 may be configured toautomatically initiate the transfer when the user opens the email orattachment.

Aspects of the present specification may also be described as follows:

1. A method for facilitating peer-to-peer message exchange, the methodcomprising the steps of: implementing a plurality of node computers inselective communication with one another, thereby forming a network,each of said node computers configured for sending an at least onemessage to a select at least one of the other node computers;implementing an at least one cache server in selective communicationwith the node computers and configured for temporarily storing at leasta portion of the at least one message when the node computer of an atleast one receiving user of said at least one message is not online; andupon a sending user of a first one of the node computers desiring tosend a message, including any file attachments thereto, to an at leastone receiving user of another one of the node computers: determiningwhether the node computer of each of the at least one receiving user isonline; for each of the at least one receiving user, upon determiningthat the node computer of said receiving user is online: transmittingthe message and any file attachments thereto directly to the online nodecomputer of said receiving user; and upon receipt, storing the messageand any file attachments thereto in memory on the online node computerof said receiving user; and for each of the at least one receiving user,upon determining that the node computer of said receiving user is notonline: transmitting the message to at least one of the at least onecache server and the online node computer of at least one otherreceiving user for later retrieval; transmitting any file attachmentsthereto having a size less than a predefined maximum size to at leastone of the at least one cache server and the online node computer of atleast one other receiving user for later retrieval; storing any fileattachments thereto having a size greater than the predefined maximumsize in memory on the node computer of the sending user; upon the nodecomputer of said receiving user subsequently going online, notifyingsaid node computer of the existence and locations of the pending messageand any file attachments thereto; and retrieving from at least one ofthe online node computer of the sending user, the at least one cacheserver and the online node computer of at least one other receiving userthe message and any file attachments thereto and storing said messageand file attachments in memory on the node computer of said receivinguser.

2. The method according to embodiment 1, further comprising the stepsof: implementing an email client in memory on each node computer, saidemail client configured for allowing a user to draft, send and receivemessages; implementing a local email store in memory on each nodecomputer, said email store configured for storing messages and any fileattachments thereto; and implementing an email agent in memory on eachnode computer, each said email agent configured for communicating withemail agents of other node computers, thereby allowing for thetransmission of the messages and any file attachments thereto directlybetween the email clients of two or more node computers.

3. The method according to embodiments 1-2, further comprising the stepsof: implementing an identity manager in selective communication witheach node computer and configured for storing a network address of theuser of each node computer along with associated encryption keys;implementing a presence manager in selective communication with eachnode computer and configured for monitoring the online status of eachnode computer; implementing a delivery manager in selectivecommunication with each node computer and configured for monitoring thelocations of any messages and associated file attachments thereto thatare pending delivery to the node computers of one or more receivingusers; and implementing a contact store in selective communication witheach node computer and configured for storing contact informationrelated to each node computer and the associated users thereof.

4. The method according to embodiments 1-3, further comprising the stepof, upon the sending user desiring to send a message, including any fileattachments thereto, to the at least one receiving user, obtaining fromthe identity manager an at least one encryption key associated with thenetwork address of each of the at least one receiving user for use inencrypting the message and any file attachments thereto.

5. The method according to embodiments 1-4, further comprising the stepsof, for each receiving user, upon determining that the node computer ofsaid receiving user is not online: notifying the delivery manager of theexistence and respective locations of the pending message and any fileattachments thereto; and querying the presence manager to determinewhich of the at least one cache server and node computer storing themessage and any file attachments thereto is currently online.

6. The method according to embodiments 1-5, wherein the step ofretrieving and storing the message and any file attachments theretofurther comprises the steps of: retrieving from at least one of the atleast one cache server and the online node computer of at least oneother receiving user the message and any file attachments thereto,having a size less than the predefined maximum size, and storing saidmessage and file attachments in memory on the node computer of saidreceiving user; upon determining that the node computer of the sendinguser is online, retrieving from the node computer of the sending userany file attachments thereto having a size greater than the predefinedmaximum size and storing said file attachments in memory on the nodecomputer of said receiving user; and upon determining that the nodecomputer of the sending user is not online, retrieving from the at leastone online node computer of another receiving user any file attachmentsthereto having a size greater than the predefined maximum size andstoring said file attachments in memory on the node computer of saidreceiving user.

7. The method according to embodiments 1-6, further comprising the stepof, upon receipt of the message and any file attachments thereto,sending an acknowledgement receipt message to the node computer of thesending user.

8. The method according to embodiments 1-7, further comprising the stepof automatically forwarding the message and any file attachments theretofrom a one of the cache servers to an at least one further one of thecache servers deemed to be relatively closer to the at least one nodecomputer of the at least one receiving user.

9. The method according to embodiments 1-8, further comprising the stepof, upon a one of the cache servers going offline, automaticallyforwarding any pending messages and file attachments thereto stored bysaid cache server to an at least one other online cache server.

10. The method according to embodiments 1-9, wherein the step ofimplementing an at least one cache server in selective communicationwith each node computer further comprises the step of implementing an atleast one cache server in memory on at least one of the node computers.

11. A method for facilitating peer-to-peer message exchange, the methodcomprising the steps of: implementing a plurality of node computers inselective communication with one another, thereby forming a network,each of said node computers configured for sending an at least onemessage to a select at least one of the other node computers;implementing an at least one cache server in selective communicationwith the node computers and configured for temporarily storing at leasta portion of the at least one message when the node computer of an atleast one receiving user of said at least one message is not online; andupon a sending user of a first one of the node computers desiring tosend a message, including any file attachments thereto, to an at leastone receiving user of another one of the node computers: determiningwhether the node computer of each of the at least one receiving user isonline; for each of the at least one receiving user, upon determiningthat the node computer of said receiving user is online: transmittingthe message and any file attachments thereto directly to the online nodecomputer of said receiving user; and upon receipt, storing the messageand any file attachments thereto in memory on the online node computerof said receiving user; and for each of the at least one receiving user,upon determining that the node computer of said receiving user is notonline: transmitting the message to at least one of the at least onecache server and the online node computer of at least one otherreceiving user for later retrieval; transmitting any file attachmentsthereto having a size less than a predefined maximum size to at leastone of the at least one cache server and the online node computer of atleast one other receiving user for later retrieval; storing any fileattachments thereto having a size greater than the predefined maximumsize in memory on the node computer of the sending user; upon the nodecomputer of said receiving user subsequently going online, notifyingsaid node computer of the existence and locations of the pending messageand any file attachments thereto; retrieving from at least one of the atleast one cache server and the online node computer of at least oneother receiving user the message and any file attachments thereto,having a size less than the predefined maximum size, and storing saidmessage and file attachments in memory on the node computer of saidreceiving user; upon determining that the node computer of the sendinguser is online, retrieving from the node computer of the sending userany file attachments thereto having a size greater than the predefinedmaximum size and storing said file attachments in memory on the nodecomputer of said receiving user; and upon determining that the nodecomputer of the sending user is not online, retrieving from the at leastone online node computer of another receiving user any file attachmentsthereto having a size greater than the predefined maximum size andstoring said file attachments in memory on the node computer of saidreceiving user.

12. A system for facilitating peer-to-peer message exchange between asending user and an at least one receiving user, the system comprising:a plurality of node computers in selective communication with oneanother, thereby forming a network, each of said node computersconfigured for sending an at least one message to a select at least oneof the other node computers; and an at least one cache server inselective communication with the node computers and configured fortemporarily storing at least a portion of the at least one message whenthe node computer of an at least one receiving user of said at least onemessage is not online; wherein, upon the sending user of a first one ofthe node computers desiring to send a message, including any fileattachments thereto, to the at least one receiving user of another oneof the node computers, said node computers are configured for:determining whether the node computer of each of the at least onereceiving user is online; for each of the at least one receiving user,upon determining that the node computer of said receiving user isonline: transmitting the message and any file attachments theretodirectly to the online node computer of said receiving user; and uponreceipt, storing the message and any file attachments thereto in memoryon the online node computer of said receiving user; and for each of theat least one receiving user, upon determining that the node computer ofsaid receiving user is not online: transmitting the message to at leastone of the at least one cache server and the online node computer of atleast one other receiving user for later retrieval; transmitting anyfile attachments thereto having a size less than a predefined maximumsize to at least one of the at least one cache server and the onlinenode computer of at least one other receiving user for later retrieval;storing any file attachments thereto having a size greater than thepredefined maximum size in memory on the node computer of the sendinguser; upon the node computer of said receiving user subsequently goingonline, notifying said node computer of the existence and locations ofthe pending message and any file attachments thereto; and retrievingfrom at least one of the online node computer of the sending user, theat least one cache server and the online node computer of at least oneother receiving user the message and any file attachments thereto andstoring said message and file attachments in memory on the node computerof said receiving user.

13. The system according to embodiment 12, further comprising: an emailclient in memory on each node computer, said email client configured forallowing a user to draft, send and receive messages; a local email storein memory on each node computer, said email store configured for storingmessages and any file attachments thereto; and an email agent in memoryon each node computer, each said email agent configured forcommunicating with email agents of other node computers, therebyallowing for the transmission of the messages and any file attachmentsthereto between the email clients of two or more node computers.

14. The system according to embodiments 12-13, further comprising: anidentity manager in selective communication with each node computer andconfigured for storing a network address of each user of the nodecomputers along with associated encryption keys; a presence manager inselective communication with each node computer and configured formonitoring the online status of each node computer; a delivery managerin selective communication with each node computer and configured formonitoring the locations of any messages and associated file attachmentsthereto that are pending delivery to the node computers of one or morereceiving users; and a contact store in selective communication witheach node computer and configured for storing contact informationrelated to each node computer and the associated users thereof.

15. The system according to embodiments 12-14, wherein the nodecomputers are further configured for, upon the sending user of the firstone of the node computers desiring to send a message, including any fileattachments thereto, to be received by the at least one receiving userof at least one of the other node computers, obtaining from the identitymanager an at least one encryption key associated with the networkaddress of each of the at least one receiving user for use in encryptingthe message and any file attachments thereto.

16. The system according to embodiments 12-15, wherein the nodecomputers are further configured for, upon determining that a given nodecomputer of a receiving user is not online: notifying the deliverymanager of the existence and respective locations of the pending messageand any file attachments thereto; and querying the presence manager todetermine which of the at least one cache server and node computerstoring the message and any file attachments thereto is currentlyonline.

17. The system according to embodiments 12-16, wherein the nodecomputers are further configured for: retrieving from at least one ofthe at least one cache server and the online node computer of at leastone other receiving user the message and any file attachments thereto,having a size less than the predefined maximum size, and storing saidmessage and file attachments in memory on the node computer of saidreceiving user; upon determining that the node computer of the sendinguser is online, retrieving from the node computer of the sending userany file attachments thereto having a size greater than the predefinedmaximum size and storing said file attachments in memory on the nodecomputer of said receiving user; and upon determining that the nodecomputer of the sending user is not online, retrieving from the at leastone online node computer of another receiving user any file attachmentsthereto having a size greater than the predefined maximum size andstoring said file attachments in memory on the node computer of saidreceiving user.

18. The system according to embodiments 12-17, wherein the nodecomputers are further configured for, upon receipt of the message andany file attachments thereto, sending an acknowledgement receipt messageto the node computer of the sending user.

19. The system according to embodiments 12-18, wherein the nodecomputers are further configured for automatically forwarding themessage and any file attachments thereto from a first one of the cacheservers to an at least one further one of the cache servers deemed to berelatively closer to the at least one node computer of the at least onereceiving user.

20. The system according to embodiments 12-19, wherein the nodecomputers are further configured for, upon a one of the cache serversgoing offline, automatically forwarding any pending messages and fileattachments thereto stored by said cache server to an at least one otheronline cache server.

In closing, regarding the exemplary embodiments of the present inventionas shown and described herein, it will be appreciated that a system andassociated methods for facilitating peer-to-peer email exchange isdisclosed. Because the principles of the invention may be practiced in anumber of configurations beyond those shown and described, it is to beunderstood that the invention is not in any way limited by the exemplaryembodiments, but is generally directed to a system and associatedmethods for facilitating peer-to-peer email exchange, and is able totake numerous forms to do so without departing from the spirit and scopeof the invention.

Certain embodiments of the present invention are described herein,including the best mode known to the inventor(s) for carrying out theinvention. Of course, variations on these described embodiments willbecome apparent to those of ordinary skill in the art upon reading theforegoing description. The inventor(s) expect skilled artisans to employsuch variations as appropriate, and the inventor(s) intend for thepresent invention to be practiced otherwise than specifically describedherein. Accordingly, this invention includes all modifications andequivalents of the subject matter recited in the claims appended heretoas permitted by applicable law. Moreover, any combination of theabove-described embodiments in all possible variations thereof isencompassed by the invention unless otherwise indicated herein orotherwise clearly contradicted by context.

Groupings of alternative embodiments, elements, or steps of the presentinvention are not to be construed as limitations. Each group member maybe referred to and claimed individually or in any combination with othergroup members disclosed herein. It is anticipated that one or moremembers of a group may be included in, or deleted from, a group forreasons of convenience and/or patentability. When any such inclusion ordeletion occurs, the specification is deemed to contain the group asmodified thus fulfilling the written description of all Markush groupsused in the appended claims.

Unless otherwise indicated, all numbers expressing a characteristic,item, quantity, parameter, property, term, and so forth used in thepresent specification and claims are to be understood as being modifiedin all instances by the term “about.” As used herein, the term “about”means that the characteristic, item, quantity, parameter, property, orterm so qualified encompasses a range of plus or minus ten percent aboveand below the value of the stated characteristic, item, quantity,parameter, property, or term. Accordingly, unless indicated to thecontrary, the numerical parameters set forth in the specification andattached claims are approximations that may vary. At the very least, andnot as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, each numerical indication shouldat least be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques. Notwithstandingthat the numerical ranges and values setting forth the broad scope ofthe invention are approximations, the numerical ranges and values setforth in the specific examples are reported as precisely as possible.Any numerical range or value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Recitation of numerical ranges ofvalues herein is merely intended to serve as a shorthand method ofreferring individually to each separate numerical value falling withinthe range. Unless otherwise indicated herein, each individual value of anumerical range is incorporated into the present specification as if itwere individually recited herein.

Use of the terms “may” or “can” in reference to an embodiment or aspectof an embodiment also carries with it the alternative meaning of “maynot” or “cannot.” As such, if the present specification discloses thatan embodiment or an aspect of an embodiment may be or can be included aspart of the inventive subject matter, then the negative limitation orexclusionary proviso is also explicitly meant, meaning that anembodiment or an aspect of an embodiment may not be or cannot beincluded as part of the inventive subject matter. In a similar manner,use of the term “optionally” in reference to an embodiment or aspect ofan embodiment means that such embodiment or aspect of the embodiment maybe included as part of the inventive subject matter or may not beincluded as part of the inventive subject matter. Whether such anegative limitation or exclusionary proviso applies will be based onwhether the negative limitation or exclusionary proviso is recited inthe claimed subject matter.

The terms “a,” “an,” “the” and similar references used in the context ofdescribing the present invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Further, ordinal indicators—such as “first,” “second,” “third,”etc.—for identified elements are used to distinguish between theelements, and do not indicate or imply a required or limited number ofsuch elements, and do not indicate a particular position or order ofsuch elements unless otherwise specifically stated. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein is intended merely to better illuminate the presentinvention and does not pose a limitation on the scope of the inventionotherwise claimed. No language in the present specification should beconstrued as indicating any non-claimed element essential to thepractice of the invention.

Specific embodiments disclosed herein may be further limited in theclaims using consisting of or consisting essentially of language. Whenused in the claims, whether as filed or added per amendment, thetransition term “consisting of” excludes any element, step, oringredient not specified in the claims. The transition term “consistingessentially of” limits the scope of a claim to the specified materialsor steps and those that do not materially affect the basic and novelcharacteristic(s). Embodiments of the present invention so claimed areinherently or expressly described and enabled herein.

All patents, patent publications, and other publications referenced andidentified in the present specification are individually and expresslyincorporated herein by reference in their entirety for the purpose ofdescribing and disclosing, for example, the compositions andmethodologies described in such publications that might be used inconnection with the present invention. These publications are providedsolely for their disclosure prior to the filing date of the presentapplication. Nothing in this regard should be construed as an admissionthat the inventors are not entitled to antedate such disclosure byvirtue of prior invention or for any other reason. All statements as tothe date or representation as to the contents of these documents isbased on the information available to the applicants and does notconstitute any admission as to the correctness of the dates or contentsof these documents.

It should be understood that the logic code, programs, modules,processes, methods, and the order in which the respective elements ofeach method are performed are purely exemplary. Depending on theimplementation, they may be performed in any order or in parallel,unless indicated otherwise in the present disclosure. Further, the logiccode is not related, or limited to any particular programming language,and may comprise one or more modules that execute on one or moreprocessors in a distributed, non-distributed, or multiprocessingenvironment.

The methods as described above may be used in the fabrication ofintegrated circuit chips. The resulting integrated circuit chips can bedistributed by the fabricator in raw wafer form (that is, as a singlewafer that has multiple unpackaged chips), as a bare die, or in apackaged form. In the latter case, the chip is mounted in a single chippackage (such as a plastic carrier, with leads that are affixed to amotherboard or other higher level carrier) or in a multi-chip package(such as a ceramic carrier that has either or both surfaceinterconnections or buried interconnections). In any case, the chip isthen integrated with other chips, discrete circuit elements, and/orother signal processing devices as part of either (a) an intermediateproduct, such as a motherboard, or (b) an end product. The end productcan be any product that includes integrated circuit chips, ranging fromtoys and other low-end applications to advanced computer products havinga display, a keyboard or other input device, and a central processor.

While aspects of the invention have been described with reference to atleast one exemplary embodiment, it is to be clearly understood by thoseskilled in the art that the invention is not limited thereto. Rather,the scope of the invention is to be interpreted only in conjunction withthe appended claims and it is made clear, here, that the inventor(s)believe that the claimed subject matter is the invention.

What is claimed is:
 1. A method for facilitating peer-to-peer messageexchange, the method comprising the steps of: implementing a pluralityof node computers in selective communication with one another, therebyforming a network, each of said node computers configured for sending anat least one message to a select at least one of the other nodecomputers; implementing an at least one cache server in selectivecommunication with the node computers and configured for temporarilystoring at least a portion of the at least one message when the nodecomputer of an at least one receiving user of said at least one messageis not online; and upon a sending user of a first one of the nodecomputers desiring to send a message, including any file attachmentsthereto, to an at least one receiving user of another one of the nodecomputers: determining whether the node computer of each of the at leastone receiving user is online; for each of the at least one receivinguser, upon determining that the node computer of said receiving user isonline: transmitting the message and any file attachments theretodirectly to the online node computer of said receiving user; and uponreceipt, storing the message and any file attachments thereto in memoryon the online node computer of said receiving user; and for each of theat least one receiving user, upon determining that the node computer ofsaid receiving user is not online: transmitting the message to at leastone of the at least one cache server and the online node computer of atleast one other receiving user for later retrieval; transmitting anyfile attachments thereto having a size less than a predefined maximumsize to at least one of the at least one cache server and the onlinenode computer of at least one other receiving user for later retrieval;storing any file attachments thereto having a size greater than thepredefined maximum size in memory on the node computer of the sendinguser; upon the node computer of said receiving user subsequently goingonline, notifying said node computer of the existence and locations ofthe pending message and any file attachments thereto; and retrievingfrom at least one of the online node computer of the sending user, theat least one cache server and the online node computer of at least oneother receiving user the message and any file attachments thereto andstoring said message and file attachments in memory on the node computerof said receiving user.
 2. The method of claim 1, further comprising thesteps of: implementing an email client in memory on each node computer,said email client configured for allowing a user to draft, send andreceive messages; implementing a local email store in memory on eachnode computer, said email store configured for storing messages and anyfile attachments thereto; and implementing an email agent in memory oneach node computer, each said email agent configured for communicatingwith email agents of other node computers, thereby allowing for thetransmission of the messages and any file attachments thereto directlybetween the email clients of two or more node computers.
 3. The methodof claim 1, further comprising the steps of: implementing an identitymanager in selective communication with each node computer andconfigured for storing a network address of the user of each nodecomputer along with associated encryption keys; implementing a presencemanager in selective communication with each node computer andconfigured for monitoring the online status of each node computer;implementing a delivery manager in selective communication with eachnode computer and configured for monitoring the locations of anymessages and associated file attachments thereto that are pendingdelivery to the node computers of one or more receiving users; andimplementing a contact store in selective communication with each nodecomputer and configured for storing contact information related to eachnode computer and the associated users thereof.
 4. The method of claim3, further comprising the step of, upon the sending user desiring tosend a message, including any file attachments thereto, to the at leastone receiving user, obtaining from the identity manager an at least oneencryption key associated with the network address of each of the atleast one receiving user for use in encrypting the message and any fileattachments thereto.
 5. The method of claim 3, further comprising thesteps of, for each receiving user, upon determining that the nodecomputer of said receiving user is not online: notifying the deliverymanager of the existence and respective locations of the pending messageand any file attachments thereto; and querying the presence manager todetermine which of the at least one cache server and node computerstoring the message and any file attachments thereto is currentlyonline.
 6. The method of claim 1, wherein the step of retrieving andstoring the message and any file attachments thereto further comprisesthe steps of: retrieving from at least one of the at least one cacheserver and the online node computer of at least one other receiving userthe message and any file attachments thereto, having a size less thanthe predefined maximum size, and storing said message and fileattachments in memory on the node computer of said receiving user; upondetermining that the node computer of the sending user is online,retrieving from the node computer of the sending user any fileattachments thereto having a size greater than the predefined maximumsize and storing said file attachments in memory on the node computer ofsaid receiving user; and upon determining that the node computer of thesending user is not online, retrieving from the at least one online nodecomputer of another receiving user any file attachments thereto having asize greater than the predefined maximum size and storing said fileattachments in memory on the node computer of said receiving user. 7.The method of claim 1, further comprising the step of, upon receipt ofthe message and any file attachments thereto, sending an acknowledgementreceipt message to the node computer of the sending user.
 8. The methodof claim 1, further comprising the step of automatically forwarding themessage and any file attachments thereto from a one of the cache serversto an at least one further one of the cache servers deemed to berelatively closer to the at least one node computer of the at least onereceiving user.
 9. The method of claim 1, further comprising the stepof, upon a one of the cache servers going offline, automaticallyforwarding any pending messages and file attachments thereto stored bysaid cache server to an at least one other online cache server.
 10. Themethod of claim 1, wherein the step of implementing an at least onecache server in selective communication with each node computer furthercomprises the step of implementing an at least one cache server inmemory on at least one of the node computers.
 11. A method forfacilitating peer-to-peer message exchange, the method comprising thesteps of: implementing a plurality of node computers in selectivecommunication with one another, thereby forming a network, each of saidnode computers configured for sending an at least one message to aselect at least one of the other node computers; implementing an atleast one cache server in selective communication with the nodecomputers and configured for temporarily storing at least a portion ofthe at least one message when the node computer of an at least onereceiving user of said at least one message is not online; and upon asending user of a first one of the node computers desiring to send amessage, including any file attachments thereto, to an at least onereceiving user of another one of the node computers: determining whetherthe node computer of each of the at least one receiving user is online;for each of the at least one receiving user, upon determining that thenode computer of said receiving user is online: transmitting the messageand any file attachments thereto directly to the online node computer ofsaid receiving user; and upon receipt, storing the message and any fileattachments thereto in memory on the online node computer of saidreceiving user; and for each of the at least one receiving user, upondetermining that the node computer of said receiving user is not online:transmitting the message to at least one of the at least one cacheserver and the online node computer of at least one other receiving userfor later retrieval; transmitting any file attachments thereto having asize less than a predefined maximum size to at least one of the at leastone cache server and the online node computer of at least one otherreceiving user for later retrieval; storing any file attachments theretohaving a size greater than the predefined maximum size in memory on thenode computer of the sending user; upon the node computer of saidreceiving user subsequently going online, notifying said node computerof the existence and locations of the pending message and any fileattachments thereto; retrieving from at least one of the at least onecache server and the online node computer of at least one otherreceiving user the message and any file attachments thereto, having asize less than the predefined maximum size, and storing said message andfile attachments in memory on the node computer of said receiving user;upon determining that the node computer of the sending user is online,retrieving from the node computer of the sending user any fileattachments thereto having a size greater than the predefined maximumsize and storing said file attachments in memory on the node computer ofsaid receiving user; and upon determining that the node computer of thesending user is not online, retrieving from the at least one online nodecomputer of another receiving user any file attachments thereto having asize greater than the predefined maximum size and storing said fileattachments in memory on the node computer of said receiving user.
 12. Asystem for facilitating peer-to-peer message exchange between a sendinguser and an at least one receiving user, the system comprising: aplurality of node computers in selective communication with one another,thereby forming a network, each of said node computers configured forsending an at least one message to a select at least one of the othernode computers; and an at least one cache server in selectivecommunication with the node computers and configured for temporarilystoring at least a portion of the at least one message when the nodecomputer of an at least one receiving user of said at least one messageis not online; wherein, upon the sending user of a first one of the nodecomputers desiring to send a message, including any file attachmentsthereto, to the at least one receiving user of another one of the nodecomputers, said node computers are configured for: determining whetherthe node computer of each of the at least one receiving user is online;for each of the at least one receiving user, upon determining that thenode computer of said receiving user is online: transmitting the messageand any file attachments thereto directly to the online node computer ofsaid receiving user; and upon receipt, storing the message and any fileattachments thereto in memory on the online node computer of saidreceiving user; and for each of the at least one receiving user, upondetermining that the node computer of said receiving user is not online:transmitting the message to at least one of the at least one cacheserver and the online node computer of at least one other receiving userfor later retrieval; transmitting any file attachments thereto having asize less than a predefined maximum size to at least one of the at leastone cache server and the online node computer of at least one otherreceiving user for later retrieval; storing any file attachments theretohaving a size greater than the predefined maximum size in memory on thenode computer of the sending user; upon the node computer of saidreceiving user subsequently going online, notifying said node computerof the existence and locations of the pending message and any fileattachments thereto; and retrieving from at least one of the online nodecomputer of the sending user, the at least one cache server and theonline node computer of at least one other receiving user the messageand any file attachments thereto and storing said message and fileattachments in memory on the node computer of said receiving user. 13.The system of claim 12, further comprising: an email client in memory oneach node computer, said email client configured for allowing a user todraft, send and receive messages; a local email store in memory on eachnode computer, said email store configured for storing messages and anyfile attachments thereto; and an email agent in memory on each nodecomputer, each said email agent configured for communicating with emailagents of other node computers, thereby allowing for the transmission ofthe messages and any file attachments thereto between the email clientsof two or more node computers.
 14. The system of claim 12, furthercomprising: an identity manager in selective communication with eachnode computer and configured for storing a network address of each userof the node computers along with associated encryption keys; a presencemanager in selective communication with each node computer andconfigured for monitoring the online status of each node computer; adelivery manager in selective communication with each node computer andconfigured for monitoring the locations of any messages and associatedfile attachments thereto that are pending delivery to the node computersof one or more receiving users; and a contact store in selectivecommunication with each node computer and configured for storing contactinformation related to each node computer and the associated usersthereof.
 15. The system of claim 14, wherein the node computers arefurther configured for, upon the sending user of the first one of thenode computers desiring to send a message, including any fileattachments thereto, to be received by the at least one receiving userof at least one of the other node computers, obtaining from the identitymanager an at least one encryption key associated with the networkaddress of each of the at least one receiving user for use in encryptingthe message and any file attachments thereto.
 16. The system of claim14, wherein the node computers are further configured for, upondetermining that a given node computer of a receiving user is notonline: notifying the delivery manager of the existence and respectivelocations of the pending message and any file attachments thereto; andquerying the presence manager to determine which of the at least onecache server and node computer storing the message and any fileattachments thereto is currently online.
 17. The system of claim 12,wherein the node computers are further configured for: retrieving fromat least one of the at least one cache server and the online nodecomputer of at least one other receiving user the message and any fileattachments thereto, having a size less than the predefined maximumsize, and storing said message and file attachments in memory on thenode computer of said receiving user; upon determining that the nodecomputer of the sending user is online, retrieving from the nodecomputer of the sending user any file attachments thereto having a sizegreater than the predefined maximum size and storing said fileattachments in memory on the node computer of said receiving user; andupon determining that the node computer of the sending user is notonline, retrieving from the at least one online node computer of anotherreceiving user any file attachments thereto having a size greater thanthe predefined maximum size and storing said file attachments in memoryon the node computer of said receiving user.
 18. The system of claim 12,wherein the node computers are further configured for, upon receipt ofthe message and any file attachments thereto, sending an acknowledgementreceipt message to the node computer of the sending user.
 19. The systemof claim 12, wherein the node computers are further configured forautomatically forwarding the message and any file attachments theretofrom a first one of the cache servers to an at least one further one ofthe cache servers deemed to be relatively closer to the at least onenode computer of the at least one receiving user.
 20. The system ofclaim 12, wherein the node computers are further configured for, upon aone of the cache servers going offline, automatically forwarding anypending messages and file attachments thereto stored by said cacheserver to an at least one other online cache server.